Universal Mobile Telecommunications System (UMTS) is a wireless communication system that is known in the art and is designed to provide higher data rates and enhanced service to subscribers. UMTS is standardized by the Third Generation Partnership Project (3GPP), including the specifications relating to the Evolved Universal Terrestrial Radio Access (Evolved UTRA) and Universal Terrestrial Radio Access Network (UTRAN). The UMTS network includes user equipment (UE, also referred to as a wireless communication device), UMTS Terrestrial Radio Access Network (UTRAN), and Core Network (CN). A UE is interfaced to cellular network elements of the UTRAN over a radio Uu interface, while the UTRAN interfaces to the core network over a wired Iu interface. The CN is generally coupled to the external network, which may include the Internet, a Public Land Mobile Network (PLMN), a Public Switched Telephone Network (PSTN), an Integrated Services Digital Network (ISDN), etc., which can exchange information to and from a UE.
The UTRAN includes multiple Radio Network Subsystems (RNSs), each of which contains at least one Radio Network Controller (RNC). However, it should be noted that the RNC may or may not be present as an actual separate network element as the logical functionality can be implemented inside a Node B. Furthermore, it should be noted that in the Long Term Evolution (LTE) of UTRAN (E-UTRAN) the RNC may not be present, but logical functions are implemented in an evolved Node B (E-Node B). The LTE may include a centralized or decentralized entity for control information. In operation, each RNC may be connected to one or multiple Node Bs, which are the network elements of the UMTS counterparts to Global System for Mobile Communications (GSM) base stations. Each Node B may be in radio contact with multiple UEs via the radio Uu interface.
The Third Generation Partnership Project Long Term Evolution (3GPP LTE) is the name generally used to refer to an ongoing effort across the industry to improve the UMTS for mobile communication to cope with continuing new requirements and the growing base of users. The goals of this broadly based project include improving communication efficiency, lowering costs, improving services, making use of new spectrum opportunities, and achieving better integration with other open standards. The 3GPP LTE project is not by itself a standard-generating effort, but will result in new recommendations for standards for the UMTS.
Communication in a cellular wireless communication system is typically established from end to end through a network. In its most simplistic terms, unlike hard-wired “landline” communications, a wireless communication device such as a UE establishes a connection to a network to carry communication data. Accordingly, a procedure is carried out between the UE and the network by means of a network element (e.g., a Node B) to establish connection. The operation, features, and advantages of wireless communication devices are well known.
An uplink access channel, broadly referred to herein as a Random Access Channel (RACH), is one typically utilized by a UE for initial access signaling to a network in instances when no dedicated or shared physical channel connection is currently established. Typically such signaling between the UE and the network on the RACH and its downlink counterpart channel is used to establish dedicated or shared channel connections mentioned above. For example, the RACH is used for initial cell access after a UE powers on. Furthermore, the RACH can be used to perform other signaling functions and data transfer functions such as a location update after the UE moves from one location to another, for initiating a call, or for user data transmission. The RACH capture procedure specified by the 3GPP requires a UE to transmit a series of access preambles, each with increasing transmit power for each access preamble attempt. Each of the access attempts is separated by an appropriate waiting time of sufficient duration to allow detection of an acknowledgment indication (AI) signal from the receiving Node B.
U.S. Provisional Patent Application No. 60/848,106 entitled “Apparatus, Method and Computer Product Providing Usage of E-DCH as RACH Shared Channel,” by J. Wigard, H. Holma, and K. Ranta-aho, filed on Sep. 29, 2006, which is incorporated herein by reference, describes using Enhanced Dedicated Channels (E-DCHs) in the random access procedure of the Universal Mobile Telecommunications System (UMTS) that allows for higher data rates and longer transmission times for a UE than the current RACH procedure. There is no collision detection mechanism in this type of RACH application. For example, as the maximum transmission time of a RACH message is 20 milliseconds (ms), and if a collision occurs (two transmitters use the same access slot and signature at the same time), the packets are lost. Nonetheless, the system automatically recovers from the collision after the transmission ends, retransmission mechanisms, higher in the protocol stack, handle a retransmission attempt in due time.
Considering that with the E-DCH random access procedure, the message length may be much longer and data rates much higher than with the current RACH procedure, the likelihood of collision at a network element is substantially increased. Thus, a system and method capable of detecting and solving the collision situation in the network, particularly in view of the E-DCH random access procedure, would be a beneficial wireless communication system enhancement.